1. Field of the Invention
This invention relates to treating subterranean formations penetrated by well bores for the purpose of reducing the production of undesirable water from the formations or reducing the loss of aqueous treating fluids to the formations.
2. Description of the Prior Art
In drilling, completing and producing subterranean formations penetrated by well bores, the in-flow or out-flow of water to and from water-bearing or water permeable formations penetrated by the well bores is often undesirable. For example, in producing oil and/or gas from subterranean formations which also contain water, the production of water along with the oil and/or gas is undesirable in that the produced water forms an undesirable emulsion with oil which can plug or otherwise interfere with efficient operation of surface separation and storage equipment and which requires special treating equipment to break the emulsion and recover oil therefrom. In addition, the produced water must be disposed of which adds to the expense of producing the wells. In instances where the well bore penetrates water-bearing formations as well as formations containing desired fluids such as oil and/or gas, the same problem exists.
In drilling, treating and completing oil and/or gas wells, highly permeable formations penetrated by the well bore often cause problems in that water from drilling muds, treating fluids such as formation fracturing fluids, acidizing fluids, packer fluids, etc., and cement slurries enter the permeable formations reducing the water content of the fluids or preventing all or part of the fluids from reaching the desired zone or formation whereby the effectiveness of the fluids is lost or reduced.
A variety of methods, compositions and means have been heretofore developed and used for plugging or sealing water-bearing or water permeable formations. For example, bulky solid materials, resinous materials and various gelatinous compounds, cement compositions and the like have been utilized heretofore for plugging subterranean formations to prevent the in-flow and out-flow of water and other fluids into and from the formations. However, such methods and compositions are generally expensive to carry out and/or are only temporarily effective. Further, such methods and compositions are generally ineffective in preventing the production of water from subterranean formations containing both water and desired fluids such as oil and/or gas.
Methods employing chemical compositions for inhibiting the flow of water in subterranean formations have been developed and used heretofore. For example, U.S. Pat. No. 3,604,508 to Marion O. Son, Jr. teaches the selective water shut-off of highly permeable subterranean formations wherein a micellar dispersion comprised of hydrocarbons, surface active agents and an aqueous medium is injected into the formation. The micellar dispersion takes up water to form a highly viscous dispersion which blocks the formation from intrusion of fluids.
U.S. Pat. No. 3,330,351 to George G. Bernard teaches a method of selectively reducing the flow of a particular fluid-producing formation into a well bore by injecting a solution containing a surface active agent into the formation followed by injecting a gas therein whereby a foam is formed in the formation adjacent the well bore which shuts off or blocks the influx of water therefrom into the well bore.
U.S. Pat. No. 3,495,664 to John Kelly, Jr. teaches shutting off water from water-producing formations in a pneumatically drilled well bore by introducing an oil wetting surface active agent and a non-volatile hydrophobic liquid into contact with the water-producing formation.
By the present invention improved methods of inhibiting the flow of water from a subterranean formation containing desired fluids such as oil and/or gas in addition to containing water are provided which are economical to carry out and which inhibit the production of water whle allowing the production of oil and/or gas from the formation. The methods of the present invention can also be effectively utilized to inhibit the flow of fluids into permeable formations penetrated by a well bore as well as inhibiting the flow of water from water-bearing formations penetrated by a well bore.